The amorphous alloy is a type of material characterized by its atomic structure arrangement being ordered in the short range while disordered in the long ranger. Duwez et al. first prepared an amorphous alloy by a rapid quenching method in 1960. Subsequently, a chemical reduction method, more economical and easier to manufacture, was developed, which can be used to prepare ultra-fine amorphous alloy particles. Amorphous alloys have received much attention from catalysis researchers since 1980 when Smith first reported the use of the amorphous alloy as a catalyst at the 7th International Congress on Catalysis.
Generally, there were two methods to prepare amorphous alloy catalysts: the rapid quenching method and the chemical reduction method. The amorphous alloy prepared by the rapid quenching method has a higher catalytic activity compared with Raney Ni catalyst, a standard method widely used in industry. However, the alloy prepared with the rapid quenching method has to be activated before it can be used as a catalyst. This activation process produces a large amount of bi-products causing environmental pollution problems, and consumes a large amount of energy due to the need to first melt the alloy. Furthermore, the rapid quenching method cannot be used to prepare amorphous alloy catalysts supported on a carrier. On the other hand, the chemical reduction method, although capable of producing amorphous alloys with a high specific surface area (the ratio of surface area to mass, m2/g), is expensive and the resulting alloys are not very thermally stable. In the addition, the process is difficult to control and so is the quality of the resulting products. These drawbacks have limited both methods' industrial applications. To overcome these problems we have introduced a new preparation method—metal inductive electroless powder plating (see Chinese Patent No.:CN1546229). Using this method, amorphous alloys and supported amorphous alloy catalyst can be easily prepared under mild conditions.
Recently, supported amorphous alloys have attracted more and more attentions, because supported amorphous catalysts have better potential of industrial applications due to their higher specific surface area, higher thermal stability, superior catalytic properties and lower cost. As a more environment friendly catalyst, the supported amorphous alloy catalyst is considered a promising substitute for Raney Ni. However, the current supported amorphous alloy catalysts have problems because it is difficult to separate them from the reaction system in some liquid phase reaction while Raney Ni catalyst can be separated easily and quickly under the same circumstances due to its larger density. This problem has seriously hampered its industrial application. In order to solve this separation problem, the applicant tried to support amorphous alloy catalyst with heavy magnesia (see Petrochemical Technology, 2005, 34, 523) and achieved some success. Heavy magnesia, however, is not an ideal support due to its low specific surface area (about 2 m2/g) and instability in water where it may be easily converted to magnesium hydroxide. Thus it remained a challenge to develop a suitable support that can overcome this problem and other problems while retaining the advantages of the supported amorphous alloy catalyst.
Expanded graphite (EG) is an intermediate product in producing flexible graphite. In industrial production, the natural flake graphite is treated with sulfuric acid and a small amount of oxidant to prepare the graphite intercalation compound. The intercalation compound is then washed and dried to obtain the expandable graphite. Heating the expandable graphite at high temperatures induces vaporization of the intercalated substances, so that a significant expansion of the material along the crystallographic c-axis occurs. The porous expanded graphite is thus obtained.
EG has been widely used in gasketing, adsorption, electromagnetic interference shielding, vibration damping, electrochemical applications, stress sensing and thermal insulator because of its chemical inertness, thermal stability, electrical conductivity, thermal insulation, innocuity, flexility, self-viscosity and perfect quality of lubricate etc. Recently there are some reports on the use of expandable graphite as catalyst (YingChun Zhou et al., Chemical Production and Technology, 2003, 10, 21), because its high specific surface area can carry a large amount of acidic groups, whereby becoming a good replacement of the liquid acid catalyst. However, there was no information concerning the use of expanded graphite as a catalyst support until the report of B. N. Kuznetsov et al. in 2003 (React. Kinet. Catal. Lett., 2003, 80, 345). They prepared a series of palladium catalysts supported on three different expanded graphite materials made with different intercalating agents, tested the prepared catalysts in hydrogenation of cyclohexene, and analyzed the effect of different intercalating agents on the catalytic activity. In the same year, Jing Zhang (Mineral Resources and Geology, 2003, 17, 713) reported the preparation and surface property study of nono-particles of EG-Metalcomplexe, which indicated the materials' potential application in the catalytic field.
In CN 1,073,726A, an alloy containing Al, rare earth elements (RE), P and Ni or Co or Fe was prepared by rapid quenching techniques. By alkaline leaching of Al from the alloy, using NaOH, a Ni/Co/Fe—RE—P amorphous alloy catalyst with high specific surface area of 50-130 m2/g was obtained. Its hydrogenation activity was greater than that of Raney Ni catalyst, a standard analyst widely used in industry.
An ultra-fine Ni—B amorphous alloy catalyst was reported in J. Catal. 150 (1994) 434-438. This catalyst was prepared by adding a 2.5 M aqueous KBH4 solution dropwise at 25° C. to an alcoholic nickel acetate solution at a concentration of 0.1 M with stirring. The resulting Ni—B catalyst was then washed with 6 ml of 8 M NH3.H2O and subsequently with a large amount of distilled water. However, ultra-fine Ni—B amorphous alloy particles obtained in this manner exhibited poor thermal stability, although their specific surface area could be as high as 29.7 m2/g.
In U.S. Pat. No. 6,051,528, a supported amorphous Ni—P and Ni—B catalyst was prepared by a chemical reduction method. The catalyst contains 0.15-30% of Ni by weight, 0.03-10% of P by weight, 0.01-3.5% of B by weight. The nickel exists in the form of Ni—P or Ni—B amorphous alloy, the atomic ration Ni/P in the Ni—P amorphous alloy is in range of 0.5-10, and the atomic ratio Ni/B in the Ni—B amorphous alloy is in range of 0.5-10. The specific surface area of the catalyst could vary from 10 to 1000 m2/g, preferably 100 to 1000 m2/g, depending on the specific surface area of the carrier.
A Ni—B amorphous alloy catalyst supported on MgO was reported in Chin. J. Catal. 2005; 26(2): 91-2. This catalyst was prepared by a metal inductive electroless powder plating method. Ag/MgO was prepared as the precursor by an impregnation method, and then the supported Ni—B amorphous alloy catalyst was prepared by an electroless plating method. Ag can anchor the initial Ni—B around it on the support and thus effectively inhibits the NiB particles from aggregation. The size of NiB clusters of the catalysts was around 40 nm. Ni—B supported on MgO exhibits better catalytic performance when compared with the unsupported catalyst.
In CN1169975A, a supported amorphous alloy catalyst was disclosed. It was composed of 0.1-30% Ni—B amorphous alloy and the metal additive M, and 70.0-99.9% porous carrier material, based on the total weight of the catalyst. The atom ratio of Ni and M is 0.1-1000, the atomic ratio of (Ni+M) and B is 0.5-10.0, its specific surface area is 10-1000 m2/g. The catalyst was prepared by contacting, at a temperature lower than 100° C., the porous material (containing of Ni and M with the atom ratio 0.1-80) with NH4+ solution at the mol concentration of 0.5-10.0 where the atom ratio of Ni to B is 0.1 to 10.0.
In CN 1286140A, a preparation method of a supported amorphous alloy catalyst composed of boron, nickel and the metal additive M was disclosed. The porous carrier material was impregnated in the solution with metal additive M, the product was dried and baked, and it was then impregnated with the solution containing nickel salt and dried. After that, the precursor was contacted with BH4− solution with the mol concentration of 0.5-15.0% at 0-100° C.
In CN 1262147A, an amorphous Ni—B alloy supported on TiO2 catalyst was disclosed. The catalyst was composed of Ni—B amorphous alloy and rare earth elements, TiO2 was used as support. The content of Ni—B is 5.26%, and the content of rare earth elements is 1%, based on the total weight of the catalyst. The prepared catalyst possesses a very high catalytic activity at low temperatures and nearly 100% selectivity in hydrogenation of aromatic compounds, and it shows good performance in hydrogenation and desulfuration, so it could be used in the hydrogenation and refinement of petrol.
In CN 1546229A a preparation method of a supported amorphous alloy catalyst was disclosed. It was composed of transition inductive metal, amorphous Ni—B alloy and oxide or molecular sieve as catalyst supports. The content of amorphous Ni—B alloy was 5-50% based on the total weight of the catalyst, and the mol ratio of Ni to B was 70:30. The content of the inductive metal was 0.1-10% based on the total weight of the catalyst. The catalyst was prepared by contacting a precursor which contained inductive metal M with a stable electroless plating solution, the amorphous Ni—B alloy will deposit on the porous support directionally with the effect of inductive metal M. The prepared catalyst showed very high catalytic activity, good mechanical property with a low cost, and it was safe for use. The preparation method was easy to apply in the chemical industrial. The preparation process would be well controlled with good repeatability in industrial production. It showed good performance in hydrogenation of compounds having unsaturated functional groups.
The preparation of supported amorphous Ni—B alloy catalyst has progress from the traditional impregnated chemical reduction method (support was impregnated with nickel salt and metal additive M first, and then it was reduced by BH4− after filtrated and dried) to the metal inductive electroless powder plating method (placing the carrier containing an inductive metal in the stable electroless plating solution containing a nickel salt and a reducing agent) which is capable of industrial-scale production (Laijun Wang et al., Chinese Journal of Catalysis, 2005, 26, 91), representing a big step forward in applying amorphous alloy catalysts in the chemical industry.
Sulfolane, or 2,3,4,5-Tetrahydrothiophene-1,1-dioxide, is a good solvent. Most of the organic compounds and polymers dissolve in sulfolane. In general, sulfolane is used for aromatic compound extraction, purification of the natural gas and refinery gases, desulfuration, and as a solvent for rubber and plastics. It also can be used in the printing process.
The industrial manufacture process of sulfolane was originally developed in England at 1940s, using butadiene and sulfuric dioxide as the starting materials. After making sulfolene by the Diels-Alder reaction, sulfolane can be obtained by hydrogenation of sulfolene at the presence of a catalyst containing nickel, which commonly is Raney Ni. Raney Ni, however, is not safe for use and it pollutes the environment. Thus, there is an urgent need to develop a novel, efficient, safe and environment friendly catalyst to replace Raney Ni.